Topography of Terminal Motor Innervation in Striated Muscles From Stillborn Infants

Christensen, E. Hohwü

doi:10.1097/00002060-195904000-00005

Cited by 134 publications

(100 citation statements)

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“…26 However, it is known that the number Dosage of BTX-A in Upper Extremity Spasticity Anne Kawamura et al 335 of neuromuscular junctions within upper extremity muscles is constant and does not increase with age. 27,28 It would, therefore, be reasonable to expect that as the pediatric patient grows into an adult, increasing the dose of BTX-A would not be beneficial. Instead, evaluating the effects of increasing dilution, volume, and number of injection sites per muscle to adjust for the increasing muscle volume and mass will probably be more important in maximizing outcome.…”

Section: Discussionmentioning

confidence: 99%

A randomized controlled trial comparing botulinum toxin A dosage in the upper extremity of children with spasticity

Kawamura

Campbell

Lam-Damji

et al. 2007

Develop Med Child Neuro

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This study compared the effects of low and high doses of botulinum toxin A (BTX‐A) to improve upper extremity function. Thirty‐nine children (22 males, 17 females) with a mean age of 6 years 2 months (SD 2y 9mo) diagnosed with spastic hemiplegia or triplegia were enrolled into this double‐blind, randomized controlled trial. The high‐dose group received BTX‐A in the following doses: biceps 2U/kg, brachioradialis 1.5U/kg, common flexor origin 3U/kg, pronator teres 1.5U/kg, and adductor/opponens pollicis 0.6U/kg to a maximum of 20U. The low‐dose group received 50% of this dosage. Outcomes were measured at baseline and at 1 and 3 months after injection, and results were analyzed with a repeated‐measures analysis of variance. There was no significant difference between the low‐dose and high‐dose groups in upper extremity function over the 3‐month period as measured by the Quality of Upper Extremity Skills Test (F[1,37]=0.18, p=0.68). There was no difference between the groups in the Pediatric Evaluation of Disability Inventory Self Care Domain (F[1,37]=0.05, p=0.83). Although grip strength decreased over the 3‐month period, there was no difference between groups (F[1,32]=0.45, p=0.51). These findings indicate that there is no difference in hand and arm function between a low dose and a high dose of BTX‐A at 1 and 3 months after injection. This information can be used to guide dosage of BTX‐A for the management of upper extremity spasticity in children.

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Section: Discussionmentioning

confidence: 99%

A randomized controlled trial comparing botulinum toxin A dosage in the upper extremity of children with spasticity

Kawamura

Campbell

Lam-Damji

et al. 2007

Develop Med Child Neuro

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“…Muscles composed of small fibres and small motor units appear to be well suited for force gradation because the fibres within each motor unit develop relatively low forces [Schmalbruch, 1985]. Thus, the extra-ocular muscles, active in fine movements of the eye, are known to be composed of a high number of motor units with small muscle fibres [Christensen, 1959;Hoogenraad et al, 1979; reviewed by Porter, 1996]. In the tongue, the fibre diameter was smaller than in limb muscles, but similar to that of oro-facial and masticatory muscles [Eriksson et al, 1982;Stål et al, 1987Stål et al, , 1990Stål and Lindman, 2000].…”

Section: Discussionmentioning

confidence: 99%

Fibre Composition of Human Intrinsic Tongue Muscles

Stål

Marklund

Thornell

et al. 2003

Cells Tissues Organs

127

115

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The muscle fibre composition of three human intrinsic tongue muscles, the longitudinalis, verticalis and transversus, was investigated in four anterior to posterior regions of the tongue using morphological and enzyme- and immunohistochemical techniques. All three muscles typically contained type I, IIA and IM/IIC fibres. Type I fibres expressed slow myosin heavy chain (MyHC), type II fibres fast MyHC, mainly fast A MyHC, whereas type IM/IIC coexpressed slow and fast MyHCs. Type II fibres were in the majority (60%), but regional differences in proportion and diameter of fibre types were obvious. The anterior region of the tongue contained a predominance of relatively small type II fibres (71%), in contrast to the posterior region which instead showed a majority of larger type I and type IM/IIC fibres (66%). In general, the fibre diameter was larger in the posterior region. This muscle fibre composition of the tongue differs from those of limb, orofacial and masticatory muscles, probably reflecting genotypic as well as phenotypic functional specialization in oral function. The predominance of type II fibres and the regional differences in fibre composition, together with intricate muscle structure, suggest generally fast and flexible actions in positioning and shaping the tongue, during vital tasks such as mastication, swallowing, respiration and speech.

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“…One hundred eighty motor neurons innervating each muscle were simulated, as intrinsic hand muscles have been reported to be innervated by a number of motor neurons in the range 90 -300 (Christensen 1959;Feinstein et al 1955;Santo Neto et al 1985). Efferent and afferent axonal lengths were set to 1 m. Alpha motor neuron axonal conduction velocity depends on neuron size (Barret and Crill 1971;Cullheim 1978;Hodes et al 1949), and in animals muscles are typically innervated by many small and fewer large neurons (Gustafsson and Pinter 1984;Heckman and Binder 1988;Hodes et al 1949).…”

Section: Methodsmentioning

confidence: 99%

The optimal neural strategy for a stable motor task requires a compromise between level of muscle cocontraction and synaptic gain of afferent feedback

Dideriksen

Negro

Farina

2015

Journal of Neurophysiology

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Dideriksen JL, Negro F, Farina D. The optimal neural strategy for a stable motor task requires a compromise between level of muscle cocontraction and synaptic gain of afferent feedback. J Neurophysiol 114: 1895-1911, 2015. First published July 22, 2015 doi:10.1152/jn.00247.2015.-Increasing joint stiffness by cocontraction of antagonist muscles and compensatory reflexes are neural strategies to minimize the impact of unexpected perturbations on movement. Combining these strategies, however, may compromise steadiness, as elements of the afferent input to motor pools innervating antagonist muscles are inherently negatively correlated. Consequently, a high afferent gain and active contractions of both muscles may imply negatively correlated neural drives to the muscles and thus an unstable limb position. This hypothesis was systematically explored with a novel computational model of the peripheral nervous system and the mechanics of one limb. Two populations of motor neurons received synaptic input from descending drive, spinal interneurons, and afferent feedback. Muscle force, simulated based on motor unit activity, determined limb movement that gave rise to afferent feedback from muscle spindles and Golgi tendon organs. The results indicated that optimal steadiness was achieved with low synaptic gain of the afferent feedback. High afferent gains during cocontraction implied increased levels of common drive in the motor neuron outputs, which were negatively correlated across the two populations, constraining instability of the limb. Increasing the force acting on the joint and the afferent gain both effectively minimized the impact of an external perturbation, and suboptimal adjustment of the afferent gain could be compensated by muscle cocontraction. These observations show that selection of the strategy for a given contraction implies a compromise between steadiness and effectiveness of compensations to perturbations. This indicates that a task-dependent selection of neural strategy for steadiness is necessary when acting in different environments.

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Topography of Terminal Motor Innervation in Striated Muscles From Stillborn Infants

Cited by 134 publications

References 0 publications

A randomized controlled trial comparing botulinum toxin A dosage in the upper extremity of children with spasticity

A randomized controlled trial comparing botulinum toxin A dosage in the upper extremity of children with spasticity

Fibre Composition of Human Intrinsic Tongue Muscles

The optimal neural strategy for a stable motor task requires a compromise between level of muscle cocontraction and synaptic gain of afferent feedback

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